Heat a skillet over medium-high heat. Lightly toast the spices (dried chili flakes and oregano; you can also add garlic if you like), then add the rest of the vegetables. Cook until the vegetables are almost done but still crisp, then push them to one side of the skillet and add the beef to sear.

Sauté everything together—vegetables and beef—so the flavors combine well, then remove from heat.

To assemble the tacos: Place a tortilla on a plate, add the filling from the skillet, top each taco with a few cilantro leaves and a lime wedge so everyone can squeeze fresh lime juice over their taco before eating.